Triangular currency arbitrage starting with 1000 USD

You hold $1000. The available conversions are: one US dollar buys $0.85$ euros; $1.5$ euros buy one pound; one pound buys $1.8$ US dollars. Trading optimally, how much profit can you make, to the nearest cent?

$20. Go dollars to euros ($850$), euros to pounds ($850/1.5\approx566.67$), then pounds back to dollars ($566.67\times1.8=1020$). The cycle multiplies wealth by $0.85\times1.8/1.5=1.02$.